In the present study, we investigated whether SDT fatty rats show impaired circadian rhythms of spontaneous locomotor activity (SLA), plasma metabolic parameters, and plasma melatonin concentrations, as well as changes in the expression of arylalkylamine-N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt) mRNA, which encode the rate-limiting enzymes for melatonin synthesis [22-24] in the pineal glands of SDT fatty rats.
Klein, "Melatonin synthesis: acetylserotonin O-methyltransferase (ASMT) is strongly expressed in a subpopulation of pinealocytes in the male rat pineal gland," Endocrinology, vol.
A simple, specific, radio-enzymatic assay for picogram quantities of serotonin or acetylserotonin
in biological fluids and tissues.
The enzymes aryl-alkyl-N-acetyltransferase (AANAT) and acetylserotonin
O-methyltransferase (ASMT), also known as hydroxyl-indole-O-methyltransferase (HIOMT), are highly conserved being detected in unicellular organisms, plants, and animals [19-21].
Although melatonin receptors, MT1 and MT2, are present in the human retina, the presence of acetylserotonin
methyltransferase (ASMT) is very low, so the receptors can bind circulating melatonin [53, 54].